| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To enable detecting easily a memory cell of deplete-defect when a power source is interrupted while operation for lowering threshold voltage of a memory element by write-in or erasing operation and a memory cell of a deplete state is caused in a nonvolatile semiconductor memory device which can be electrically written and erased, and which has constitution in which a plurality of memory cells such as AND type and NOR type flash memories are connected to a common bit line and a source line in parallel. <P>SOLUTION: In inputting the prescribed command or in applying a power source, it is detected whether a current is made to flow in a memory cell or not by making all word lines a non-selection state and turning on selecting switches (Qs11-Qs1k, Qs21-Qs2k) provided at the bit lines by a sense amplifier to which the bit lines are connected and it is determined whether a memory cell of a deplete-state resists or not. And when the memory cell of the deplete-state exists, voltage (Vss or negative voltage) of a selection level is applied to one of word lines in order, the residual word lines are made a non-selection level (negative voltage or Vss). <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
